1. Field of Invention
The present invention relates to an electric machine. In particular, a homopolar motor-generator is disclosed.
2. Discussion of the Related Art
Simple homopolar motors have been known since discovery of the Faraday motor in 1831. In Faraday's invention, a current carrying wire hanging alongside a bar magnet included in the circuit revolves about the magnet due to interaction of the two magnetic fields. Faraday's motor illustrates “Lorentz forces” which are at right angles to both the direction in which a charged particle is moving and the direction of an applied magnetic field. The simple application of the Lorentz force equation (‘crossing’ the direction, v, of the current into the direction, B, of the magnetic field) yields a rotational force.
Homopolar motors and homopolar motor-generators (“homopolar machines”) are not widely used in practice and have not generally been the subject of academic research or industrial development. Explanations for this paucity of interest in homopolar motors likely includes the homopolar motor's use of only half of the magnetic flux density resulting in a machine that has twice the volume of competing machines such as synchronous reluctance machines.